Influence of material extrusion parameters on tensile performance of carbon fiber-reinforced PETG and PLA composites: An ANOVA based optimization study

Carbon fiber-reinforced thermoplastics processed by Material Extrusion (MEX) possess great potential for lightweight structural applications because to their superior mechanical properties and manufacturing flexibility. In this study, the impacts of six important MEX process parameters, layer height, extrusion temperature, printing speed, infill density, extrusion multiplier and raster orientation, on the tensile performance of carbon fiber-reinforced PETG (PETG-CF) and PLA (PLA-CF) composites are examined. An experimental design based on response surface methods, with 54 runs, was used. Tensile strength and Young’s modulus were assessed according to ASTM D638. The significance of the parameters was assessed using ANOVA, and predictive models and optimal processing conditions were obtained via desire-based multi-response optimization. The main parameters were the infill density and the extrusion multiplier, which had strong interaction effects. Maximum Young’s modulus (612.2 MPa) was reached for PLA-CF, and maximum tensile strength (34.1 MPa) for PETG-CF. The best parameters were: layer height 0.25 mm, printing speed 30 mm/sec, infill density 66%, extrusion multiplier 0.80, and raster orientation 15°. The response surface models exhibited R 2 values ranging from 0.8189 to 0.9216 and predicted R2 values ranging from 0.7042 to 0.8920, with prediction errors less than 1% in the experimental validation. The developed optimization framework and predictive models provide practical manufacturing guidelines to improve the tensile performance of lightweight composite structures and serve as tools for process planning in high-performance additive manufacturing applications.